For Christmas, it's nice to feature a goody on one's website to participate to the overall merrier atmosphere. A favorite and immemorial web touch is the snow fall. It used to be popular on UNIX boxes as well though it apparently isn't so standard nowadays. As for the good old web, we like to use Scott Schiller's snowstorm, bringing snow to the web since 2003.
In our case, we can safely restrict to the portion of the screen that contains the header, since the snow is not visible elsewhere or is very ugly if of a different color.
this.flakeBottom = 230; // Integer for Y axis snow limit, 0 or null for "full-screen" snow effect